Remote control system



Search R001 60-573. 0R 2,363,479 SR Nov. 28, 1944. F. v. BROWN 2,363,479

REMOTE CONTROL SYSTEM Filed Jan. 12, 1943 6 Sheets-Sheet 1 w. www mSearch R0 NOV. 28, 1944. v, BROWN 2,363,479

REMOTE CONTROL SYSTEM Filed Jan. 12, 1943 6 Sheets-Sheet 2 Nov. 28,1944. F. v. BROWN '1 2,363,479

' REMOTE CONTROL SYSTEM Filed Jan. 12, 1943- e Sheets-:Sheet3 "w.FOX-"KER PLANTS.

NOV. 28, 1944. v, BROWN 2,363,479

REMOTE CONTROL SYSTEM Filed Jan. 12, 1943 6 Sheets-Sheet 4 Nov. 28,1944. v? BROWN 2,363,479

REMOTE CONTROL SYSTEI Filed Jan. 12,1943 6 Sheets-Sheet 5 $821113! KUUNov. 28, 1944. v, BROWN REIOTE CONTROL SYSTEM 6 Sheets-Sheet 6 L la/9slight movements of the kind referred to.

Patented Nov. 28, 1944 UNITED STATES PATENT OFFICE Application January12, 1943, Serial No. 472,120 In Great Britain January 22, 1942 Claims.

This invention relates to remote control systems wherein either ahydraulic or a mechanical transmission is used between the mastercontrol and the sub-control unit sometimes called a motor or receiverunit.

In the specification belonging to my United States Patent No. 2,308,048,dated January 12, 1943, I have described and claimed a remote controlsystem wherein variations in volume or length of the transmission mediumor means are compensated by the aid of a mechanical linkage comprisingeccentrics of oppositely disposed eccentricity around a common centrehaving their Straps coupled with a device constrained to move in onedirection only, the said eccentrics being normally free to adjustthemselves revolubly, simultaneously under the influence of the saidvariation but constituting with their straps a locked mechanism when thetransmission is operatively stressed. In mechanisms of this kind andwith the eccentric straps having a pivotal connection with a crossheadguided for rectilinear movement, errors can develop arising from thecondition of clearanc between the eccentric and eccentric strap,essential to free rotation of the eccentric within the strap. In effecton each occasion the mechanism might be operatively stressed the moreheavily loaded eccentric strap in the .process of binding on to itsmating eccentric squeezed the clearance to one side swinging veryslightly relative to the crosshead during the squeezing action. Theerror can develop in a cumulative manner in consequence of successive Itis one of the objects of the present invention to provide an improvedeccentric mechanism which is adapted for use in apparatus wherein a highdegree of accuracy is demanded, and which is so contrived as to preventpossibility of the cumulative error referred to.

Furthermore, in eccentric mechanisms of the kind referred to and whenused in apparatus designed for a relatively great length of transmissionor possessing a relatively high volumetric capacity, it is possible forthe two eccentrics to perform their simultaneous but opposite revolublemovements, under the effect of either one continuous variation orsuccessive variations, to such an extent as to bring their centres ofeccentricity into coincidence. When this happens, it is not possible tocause the straps to bind upon them, when such straps are operated by ahand control lever. When this condition is reached, the straps wouldsimply move idly around the eccentrics and fail to operate the controlsystem unless suitable provision is made. It i a further object of thepresent invention, therefore, to devise means for dealing with thisabnormal condition of the mechanism.

According to the present invention, a remote control system, whereinvariations in Volume or length of the transmission medium or means arecompensated by the aid of a mechanical linkage comprising oppositelydisposed eccentrics, is distinguished by the eccentrics having theirstrap devices formed a sliders movable in rectilineal guides, the saideccentrics being normally free to adjust themselves revolublysimultaneously under the influence of the said variations, during whichrevoluble adjustments the sliders move along their guides, butconstituting with their strap devices or sliders a locked mechanism whenthe transmission is operatively stressed. In the case of a hand controllever being used in the system the guides are provided in a hubformation of such lever. Anti-friction bearings, such as rollerbearings, are suitably provided between respective slides and eccentricsand such bearings may, if desired, be put under initial stress when theparts are assembled. Thus, when the eccentrics are turned simultaneouslyin opposite directions, due to the aforesaid variations and assumingthat the control lever has a normally upwardly inclined position, one ofthe slides is moved upwards in its guide and the other is moveddownwards in its guide. Upon the swingin over of the control lever atany time for the operation of the transmission, the sliders instantlybind between the guides and upon respective eccentrics and with no lagin the binding of the one as compared with that of the other.

During the normal operation of the mechanism it may be that theeccentrics will arrive in a position in which their eccentrics coincide,in which event the control lever would be swung and the sliders would beturned idly about the eccentrics. To avoid this, an automatic lockingdevice is provided which causes the sliders to bind on the eccentricswhen the control lever is swung with the eccentrics in the position ofcoincidence. The application of the eccentric mechanism to pistons usedas compensators only and not as part of a master control, will behereinafter fully explained.

In order that the invention may be readily understood reference is madeto the accompanying drawings, in which:

Figure 1 is partly a side elevation and partly a l gitudinal section ofa master control fitted with the present improvements and adapted foruse on a hydraulic control system.

Figure 2 is a fragmental longitudinal section to a larger scale of partsseen in Figure 1.

Figure 3 is a side elevation (as seen from the right hand side of Figure4) of a hand control lever fitted with the eccentric devices of theseimprovements.

Figure 4 is a view as seen from the left hand of Figure 3 but with anexternal part broken away to disclose the mechanism within.

Figure 5 is similar to Figure 3 but as seen from the opposite side andwith an external part broken away to disclose the mechanism within.

Figure 6 is a cross section of the eccentric mechanism of theseimprovements, the eccentrics having been turned so that theireccentricities coincide.

Figure 7 is an elevation as seen from the right hand side of Figure 6.

Figure 8 is a view similar to Figure 6 but showing the eccentrics afterthey have been turned a little in opposite directions from the positionshown in Figures 6 and 7.

Figure 9 is an elevation as seen from the right hand side of Figure 8.

Figures 10 and 11 are diagrammatic views explaining the operation of theparts seen in Figures 6 to 9 Figure 12 is a perspective view of a remotecontrol hydraulic system incorporating a compensating mechanism to whichthe eccentric mechanism of these improvements is applied, instead ofbeing applied to the master control.

Figure 13 is a longitudinal sectional view of the compensating mechanismseen in Figure 12..

Figure 14 is a cross-section of Figure 13.

Figure 15 is a fragmental sectional view illustrating to a larger scalecertain parts seen in Figure 13.

Figure 16 is a sectional elevation of the eccentric mechanism embodiedin the compensating mechanism illustrated in Figures 13 and 14.

Figure 17 comprises both a side elevation and a plan to a larger scaleof one of the locking pins seen in Figure 16.

Figure 18 is a plan of Figure 16.

Figure 19 is an elevation as seen from the left hand side of Figure 18.

Figure 20 is a sectional elevation to a larger scale of a wedge adjusteremployed in the mechanism illustrated in Figures 16 and 18, and

Figure 21 is an elevation as seen from the left hand side of Figure 20.

Referring to Figure 1 of the drawings, a and b are two hydrauliccylinders alike in construction and operation, excepting that when thepiston c of one is at the end of its outward stroke, the piston of theother cylinder is at the end of its inward stroke. The cylinder b isseen to be fitted on one end with a nozzle piece b wherein is fr rmed ascrew-threaded socket b for the tight jointing of a pipe leading to oneend of the motor uni The nozzle piece b is also fitted with a screw plugb normally closing a bleed hole. the latter being opened to permitescape of air when the system is charged with liquid. The cylinder a isfitted with a similar nozzle piece (1 Compression springs d one Withinthe other constantly tend to keep each piston c at the end of itsoutward stroke. The piston c of cylinder 12 is shown beyond the end ofits outward stroke because there is no pressure present to force it backand put its spring (1 under further compression. Each piston is inoperative connection with a cyli drical rack e or e see also Figure 4,which meshes with a respective pinion f or J. The teeth of the rack e inthe cylinder b are upwardly presented so as to mesh beneath therespective pinion f whereas the teeth of the rack e in the cylinder aare downwardly presented so as to mesh on top of the respective pinionf. If expansion of the liquid in the hydraulic system should occur, thepistons c in both cylinders a and b are forced rightwardly in Figure 1against the action of their springs (1. Owing to the meshing justexplained each piston movement will drive the respective pinions inopposite directions. On the contrary, if contraction of the liquidshould occur, the pistons c are forced leftwardly by respective springsd and the pinions are again driven oppositely to one another but in thereverse direction as compared with the direction of revolution whenexpansion occurred. If there should be a slight loss of liquid fromeither of the pipe lines, the piston in the cylinder affected follows uprecession of the liquid under the urge of an auxiliary spring d and islocked in its new position and prevented from being hydraulicallypressed back into the old position by means of a one-way ball clutchdevice g seen in detail in Figure 2. This clutch permits the rod of thepiston to move leftwardly in relation to its rack e or e but prevents itfrom moving rightwardly in relation to such rack. When the liquid chargein a system is to be replenished, the pistons must be permitted to moveback to a normal position under the pressure of the liquid. For thispurpose a so-called lifter tube I5 is provided which when pushed in isable to release the ball clutch device. This lifter tube is of similarnature to that described in the specification of my U. S. Patent No.2,308,048 and therefore needs no further description here.

As will be seen clearly from Figures 3 and 4, the pinion f is fixedlymounted on a shaft h of an eccentric 7 and the pinion f is fixedlymounted on a hollow shaft h of an eccentric 7' the hollow shaft h beingrevolubly sleeved on to the shaft h. Thus, equal and opposite movementsof the pinions f and I will produce similar equal and opposite movementsof the eccentrics 7' and 7' Normally, the eccentrics 7' 7 as viewed inend elevation have their eccentric radii directed oppositely but at thesame angle from a neutral line. Thus, when viewing the mechanism inFigure 4 from the left-hand side. the eccentric a may have its eccentricradius displaced counter-clockwise by a given angle from a neutralradius in which case the eccentric would normally have its eccentricradius displaced clockwise by a similar angle from the said neutralradius.

In the construction according to the :present improvements, theso-called strap devices, in which the eccentrics 7 7' are operativelyengaged, are sliders l Z Figures 4 and 5, guidingly mounted forrectilinear movement only in a hub or housing of the hand lever 70. Inthe specification belonging to my prior aforesaid Patent No. 2.308.048,the strap devices were rings having lugs pivotally connected with acrosshead, the latter being carried by a stem having rectilinealguidance. In both mechanisms, however, the eccentries are normally freeto adjust themselves revolubly simultaneously under the influence ofvariations in volume or length of the transmission medium or means butconstitute with their strap devices a locked mechanism when thetransmission is operatively stressed. Thus, and as will be understoodfrom Figures 4 and 5, if the eccentrics OJ: L L

oc'cuuu nuul r and 1' are oppositely disposed as described above, theycan freely be turned simultaneously in opposite directions and throughequal angles by their pinions and f such turning simply resulting in oneslider l or Z rising in its guides in the housing 70 and in the otherslider moving downwards in its guides. The mechanism is thus free tocompensate for variations in the transmission as already explained. Ifthe master control is to be operated, the hand lever is is grasped andturned through an angle as for example, leftwardly from the positionseen in Figure 1. Immediately such hand pressure comes upon the lever,the strap devices or sliders l I will bind between the guides and onrespective eccentrics because of the tendency to turn them in one andthe same direction about different centres. Such binding action isimmediate and effectual for turning the shafts 71. W, in view of thesaid strap devices being con fined closely by the rectilineal guides inthe housing k and the sole possible relative movement of such devicesbeing rectilineal in such guides.

In the example illustrated, and as will be clear from Figures 4 and 5, aball or roller bearing m may be interposed between each of theeccentrics and its strap device, so that the eccentric a 7' may beturned easily by their pinions f 1 during the compensating movementsabove described. In order to avoid any slackness in these bearings, suchas might introduce slight errors when the control iseXercised. the said"bearings 122 may be put under initial stress when the parts areassembled.

After a period of use, involving a number of similar compensatorymovements by the eccentrics 7' 7' in which movements each turns througha small angle oppositely to the other, it may be that the eccentricswill arrive in a position in which their eocentricities coincide. This iassumed to be the case in Figure 10, from which it will be understoodthat if the control lever is then swung so as to exert through thehousin k a couple as indicated by the arrows, the two sliders Z Z wouldbe idly turned about the eccentrics :i i seeing that both are free torevolve about the common centre at. During such tuming, the two sliderswould be moved freely by their eccentrics in one and the samerectilineal direction in the guides. Thus, no torque would betransmitted to the shafts h h It will be apparent, however, that if theslides could be prevented from performing this rectilineal slidingmovement during such turning. they would then bind upon the eccentrics,so that a torque would be imparted to the shafts h h These improvementstherefore further provide an automatic locking device now to bedescribed, for causing the sliders to bind on the eccentrics when thecontrol lever is swun with the eccentrics in the position in which theirradii of eccentricity coincide.

Referring to Figures 4 to 9, the automatic locking device comprises aplate n disposed between the juxtaposed eccentric a 7' and their slidersl 1 this plate 11. being revolubly fitted on the control shaft h. Endportions 11 of this plate extending beyond the ends of the sliders Z Zare thickened and such end portions are formed with transverse bores oin which are slidingly received short cylindrical pins p with roundedends. The outer ends of the sliders 1 1 at those edges which are sitedirections by their pinions f I one of the sliders l l is moved up inits guides and the other is moved down. The action at each end of thesliders is similar, for as one bevelled edge q moves away from therounded end of the pins p at one side, see th top left-hand part ofFigure 8, it leaves the pins p free to move laterally under the cammingaction of the bevelled edge q at the opposite side. Figur 8 representsthe eccentrics when they have turned oppositely to one another so thattheir radii of eccentricity no longer 00- incide, as is indicated by thediagram lines in Figure 9. Comparing Figure 8 with Fi ure 6 which showsthe eccentrics in the position in which their radii of eccentricitycoincide, it will be seen that the pins 10 at the top of the figure havebeen cammed leftwards and that the pins 1) at the bottom of the figurehave been cammed rightwards. The radii of throw of the eccentrics shownby E in Figure 9 is magnified for purposes of illustration in Figures 10and 11 as will be understood.

With the eccentrics 7' 7' not coincident and in a position such as isshown in Figure 8, any turning of the hand lever k and housing k willimmediately cause the sliders l l to bind on the eccentrics as alreadyexplained. With the eccentrics in the coincident position shown inFigure 6, and if the plate n and pins p were not present, turning of thehand lever k, to exert the couple indicated by the arrows, would merelycause the sliders Z Z to turn idly around the eccentrics 7' :i as hasalready been explained by reference to Figure 10. With the presentinvention, however. if the hand lever is turned with the eccentricscoinciding as in Figure 6, the tendency for the sliders Z l to be movedby their eccentrics rectilinearly and simultaneously in the samedirection is prevented by the pins p, because these pins are carried bythe plate n, which is revoluble around the centre 11 of the shaft h, seeFigure 11, Whereas the sliders Z Z if free to do so would turn about thecentre a: as already explained. If in the turnin movement, the tendencyis for the two sliders l l to move simultaneously upwards in theirguides in Figure 6, such movement is prevented by the pins p at the topengaging between the sliders and the thickened top end of the plate n.Consequently, the locked sliders Z Z are constrained to turn about theshaft centre y, as indicated in Figure 11, and in so doing bind on theeccentrics 7' 1' and turn the latter so that a torque is imparted to theshafts h M.

With the particular eccentric mechanism described in the specificationof my Patent No. 2,308,048 aforesaid, it was necessary to re-set theeccentrics from time to time and particularly when their radii ofeccentricity approached 00- incidence. With the improved mechanism justdescribed, however, it is possible for the eccentrics to continue torevolve step by step simultaneously and in opposite directcns for thecompensation of variations, even after they have reached the positionwherein their radii of eccentricity coincide. Having passed thisposition and re-attained positions of opposite eccentricity, asdescribed with reference to Figure 8, the normal operation of the partswill be resumed during subsequent operations of the control lever k anduntil the eccentrics again come into coincidence. The improvedmechanism, therefore, is very suitable for installations wherein aconsiderable distance exists between the master control illustrated inthe drawings and a distant motor unit controlled by it, so that aconsiderable total variation in the volume of the transmission medium,or in the length of the transmission means, must be catered for.

As will be clear from Figures 3 to 5, the hand control lever is and itshub or housing k may be made from a tube of metal by several operationswhich result in one end of the tube becoming enlarged and flattened intothe form of the housing k suitable for guiding the sliders Z Z in themanner described. As seen best in Figure 5, the end portion k of thehousing may be separately formed as a removable cap. As seen in Figures3 and 4, the lever is may be pivotally supported by having one wall ofits hub k formed with a hole which is revolubly engaged with aneccentric bush t surrounding the hollow shaft h Referring now to Figure12, on the right hand in the figure, there is a master control unit comprising a master control lever M which is operative for moving a doubleacting piston in a cylinder M. On the left hand in the figure, there isa so-called motor unit comprising a cylinder S containing adouble-acting piston to be moved in accordance with any movementimparted to the master control piston. The ends of the piston rod of themotor unit are seen in the figure, and such ends are operativelyconnected with any part to be operated or controlled by such motor unit.T indicates an armoured tubular casing enclosing twin pipes boundclosely together along their length by heat insulating material. At itsends, the tubular casing T is fitted with Y-pieces T and T. The ends ofthe twin tubes are separated and passed through respective branches ofthe Y- pieces. At the right-hand side of the figure, the end portions ofthe twin tubes passing through respective branches of the Y-piece T areconnected with respective ends of the master cylinder M and at thelefthand side of the figure, the end portions of the twin tubes passingthrough respective branches of the Y-piece 'I are connected withrespective ends of the motor unit cylinder S At a convenientintermediate point in its length, the tubular casing T is divided andthe divided ends have connected with them Y- pieces T Divided endportions of the twin tubes are passed through respective branches of theY- pieces T and are connected by the latter with a chest D. The latternormally provides a throughway connection between the branches '1' ofthe Y-pieces T, which branches T appertain to one of the twin tubes. Thechest D also normally provides a through-way connection between thebranches T which appertain to the other one of the twin tubes. The twothrough-way connections in the chest are, of course, normally isolatedfrom one another. The chest D further provides communication between oneof the through-way connections and a compensator cylinder C and betweenthe other one of the through-way connections and a compensator cylinderC Thus each of the twin tubes connects one end of the master cylinder Mwith a corresponding end of the motor unit cylinder S and,intermediately, s in communication with a compensator cylinder throughthe chest D. The compensator cylinders C C, which contain spring loadedpistons as hereinafter described, are supported in a body casting C anda box B supported on this castin encloses the eccentric mechanism ofthese improvements also as hereinafter described.

Referring to Figure 13. it will be seen that the compensator cylinder Conly is in section but it will be understood that the compensatorcylinder C seen only in elevation, is of precisely similar constructionand has the same internal arrangements as the cylinder C. Each cylinder,ha within it a piston I which is separat from its piston rod 2.Slidingly fitted within each cylinder is a hollow cylindrical part 3(see also Figure 14) which is formed along its length with rack teethfor meshing with pinions f f similar to those described with referenceto Figures 3 and 4. As will be seen in Figure 14, the walls of thecylinders C C are cut away to form openings in which the rack teeth areexposed so that they can freely mesh with respective pinions ,f 1Referring again to Figure 13, the right-hand end of the cylindrical rack3 is abutted against an annular shoulder 9 of a tubular sheet-metalspring cup 4. The latter encloses a long loading spring 5 of smalldiameter and a shorter loading spring 6 of larger diameter and theannular shoulder 9 aforesaid occurs at the point where the largerdiameter end portion of the cup 4, enclosing the spring 6 of largerdiameter, merges into a portion of the cup which is of reduced diameterto suit the spring 5 and to fit within the rack 3. The springs 5 and 6are compression springs and the spring 5 acts between an end cap I,suitably fixed on the cylinder, and an annular shoulder 8 (Figure 15)formed by reducing the inner end of the cup 4, whilst the spring 6 actsbetween the said cap 'I and the shoulder 8 aforesaid. Thus, the twosprings 5 and 6 constantly tend to force the cup 4 leftwardly and suchforce is transmitted to the cylindrical rack 3 by the annular shoulder9. By using a suitable combination of springs of different lengths anddiameters, it is possible to provid a spring loading of desirablerating. Within the left-hand end of the cylindrical rack 3 there istightly inserted a thimble device III (Figures 13 and 15) the bore ofthe thimble being gradually reduced at an intermediat point so as toproduce a tapered surface II (Figure 15) A ball cage I2 contains a setof balls I 3 which operate as a ball clutch between the thimble and thepiston rod 2. An auxiliary compression spring I4 operates between theball cage I2 and a flanged fitting 2 on the end of the piston rod 2. Thepiston l and piston rod 2 are shown in Figure 13 in an extreme leftwardposition, such as they would occupy when the system is not charged withliquid. It will be understood, however, that when the system is chargedwith liquid under pressure, such liquid entering at the end of thecylinders will force the pistons I and piston rods 2 rightwardly fromthe position illustrated, thereby putting the springs 5 and 6 underadditional compression. When the system is charged with liquid underpressure and the pistons I in the two cylinders are forced rightwardsfrom the position seen in Figure 13, if a rise of temperature shouldcause expansion of the liquid in the system, the two pistons I will beforced farther to the right against the resistance of the spring 5 and6. If contraction of the liquid in the system should occur, due to afall in temperature, then the two pistons I will move leftwardly underthe urge of the springs 5 and 6. In view of the fact that the twin tubesconnecting the master control with the motor unit are closely juxtaposedalong their length within a common casing T, a explained with referenceto Figure 12, the expansion or contraction in one will always bereasonably equal to that in the other, so that the two pistons I willalways be equally affected. In the event of a slight leakage from one ofthe tubes, so that liquid recedes from a .piston I, the latter is causedto follow up and maintain pressure contact with the liquid by the actionof the auxiliary spring I.

The latter operates in comprmsion between the ball cage l2 and theflanged fitting 2. It will be observed that due to the one-way action ofthe ball clutch l3, the rod 2 is free to move leftwardly relatively tothe cylindrical rack 3, the balls declutchingly rolling along the taperH towards the enlarged bore of the thimble I0. Opposite movement of therod 2, that is to say rightwardly relatively to the cylindrical rack 3,is not possible because the balls |3 are then jammed between the rod 2and the contracting bore of the tapered part II. Each piston I isconsequently always maintained in full pressure contact with the liquidwithin its cylinder and cannot move back from the position in which itmakes such contact. When the liquid charge in a system is to bereplenished, the pistons must be permitted to move back to a normalposition under the pressure of the liquid. For this purpose a so-calledlifter tube I5 is provided. As Will be clear from Figure 15, the liftertube I5 is sleeved along the rod 2 and both it and the rod 2 extendthrough the cap 7, Figure 13, the end l5 of the tube being fashioned sothat it can be grasped between finger and thumb. The inner end of thetube is flanged at l5 thi flange being engaged with an inturned flangeHi on one end of a short cylindrical sleeve l6 slidable on the inner endportion of the spring cup 4. The other end of the sleeve l6 has anout-turned flange Hi which forms an abutment for one end of a smallcompression spring 11, the opposite end of the latter being abuttedagainst the end of the thimble I0. It will now be seen that the liftertube |5 can be pushed to the left, against the action of the spring soas to engage the ball cage I2 and move the balls |3 into de-clutchingposition. This permits the piston to be moved inwardly by the liquidpressure and the rod 2 to move rightwardly in relation to thecylindrical rack 3. When this operation is finished and finger pressureis released from the part li the spring ensures the return of the liftertube l5 to its normally inoperative position.

It will be apparent that when the master control handle M Figure 12, isoperated, one side of the piston in the cylinder M forces liquid throughone of the tubes to one side of the motor piston in the unit S liquiddisplaced by the other side of the motor piston being returned throughthe other tube to the other side of the master piston. During such anoperation the pressure in one of the tubes and in one of the cylinders CC is greater than that in the other. Consequently, the piston I, Figure13, subjected to the greater pressure would move rightwardly in itscylinder and prevent the motor piston from being properly operated, ifit were not for the action of the mechanical linkage of theseimprovements now to be described. This linkage, as will be seen, iseffective for permitting simultaneous equal movements in one and thesame direction and for preventing movement of one piston relatively tothe other when the master control is operated.

The mechanical linkage, which is an eccentric mechanism generallysimilar to that described with reference to Figures 3 to 11, iscontained in a housing l8 which is detachably mounted on the body C bymeans of two parallel pins I9, Figures 13 and 14. The details of thiseccentric mechanism are illustrated clearly in Figures 16 to 21. As inthe preceding construction, the pinion f is fixedly mounted on one endof a central shaft h which has fixedly mounted at its other end aneccentric :i. The pinion f is fixedly mounted on one end of a hollowshaft h revolubly sleeved on to the shaft h, the other end of the shaftn having fixedly mounted on it an eccentric 7' The eccentrics 1' 7' workin holes in respective slides Z 1 a ball bearing m which may beinitially stressed being interposed between each eccentric and itsslider. The sliders Z Z are guided rectilinearly in the housing l8 bymeans of a brass or other bearing strip 20, Figure 18, at one side andby means of an adjustable bearing strip or pad 2|, Figures 18, 20 and21, at the other side. The adjustment of the bearing strip or pad 2|will be clearly understood from Figures 20 and 21, wherein it will beseen that at the rear the strip or pad 2| is formed with inclinedsurfaces 22 which slidably engage similarly inclined surfaces of a wedgemember or gib 23. A pin 24 passed through a hole in the gib 23 is formedwith a diametrical screw-threaded hole to serve as a nut for anadjusting bolt 25, the head 26 of which bears against the bearing pad2|. The end of the pin 24 projecting beyond the gib 23 is engaged in ahole in a wall of the housing I8, Figures 16 to 18, so that the gib 23cannot move longitudinally. It will be seen, therefore, that by turningthe bolt 25 by means of a key or wrench applied to the head 26, the saidbolt will screw itself through the nut and force the bearing pad 2| toslide longitudinally along the gib 23. Owing to the wedging actionproduced by the inclined surfaces 22, the bearing pad 2| is thustightened against the sliders 1 1 so that the latter are slidable in theclosest possible contact relation with the bearing strip 20 and bearingpad 2|. Absence of slackness and the maintenance of substantialtightness at thesebearing faces is important for the accurate working ofthe eccentric mechanism.

The automatic locking device in Figures 16 and 18 comprises a plate nsimilar to that described with reference to Figures 6 to 9, but whereasin the latter figures the plate was fitted with pins p having roundedends for engaging with the bevelled surfaces q of the sliders 1 1 inFigures 16 to 18 pins p have end portions removed to provide fiatsurfaces 12 for engaging with the bevelled surfaces q. The reason forthis is to avoid wear and prevent indentation of the bevelled surfaces qby the pressure of the ends of the pins against them. A ball bearing 21provided on the shaft h Figures 16 and 18, is inserted into andsupported by the body C when the parts are mounted in position as inFigure 14.

As already explained with reference to Figure 13, the pistons in the twocylinders C C can simultaneously move inwardly in their cylinders underthe efiect of pressure due to expansion of liquid in the system andagainst the resistance of the loading springs 5 and 6, Or, they cansimultaneously move outwardly under the urge of the loading springs 5and 6 when contraction of the liquid in the system takes place. Whenthese simultaneous and like movements of the pistons take place thepinions ,f F, Figures 14, 16 and 18 are turned by the racks 3 and theeccentrics a are turned equally and oppositely in their respectivesliders 1 1 This produces sliding movements of the sliders l l inopposite directions and, as in Figures 6 to 9, such opposite movementsof the sliders l I produce transverse movement of the pins p by reasonof the camming action of some of the bevelled surfaces q against thebevelled surfaces W of the pins 12 When the master control handle MFigure 12, is operated in one direction or the other to produce similaroperation of the motor unit S this will set up a greater pressure in oneof the twin tubes of the transmission, because that tube is transmittingthe power for overcoming whatever load there may be on the motor unitwhereas the other tube is merely returning to the master controlcylinder the liquid displaced from one end of the motor unit cylinder.Consequently, the piston I in one of the cylinders C, C will besubjected to a greater pressure than the piston in the other cylinder.If the eccentric mechanism of these improvements were not present, thepiston l, subjected to the greater pressure might move inwardly againstits spring loading with the result that the motor unit would not beoperated or not accurately operated. With the eccentric mechanismmounted and operative as hereinbefore described, the instant that thereis a tendency to move one piston not simultaneously with and in the samedirection and to the sam extent as the other piston, the correspondingeccentric 7' or i Figure 16, will tend to turn alone. In order to beable to turn, however, this eccentric must be able to move its slider lor Z but this is impossible for, owing to the locking pins p the oneslider can only move if at the same time the other slider movesoppositely to permit the pins 17 to be cammed transversely of thesliders as already explained. Consequently, the eccentric mechanism isjammed and positively prevents any such individual movement of one ofthe pistons I. This jamming effect will be obtained even when theeccentrics :i 7' have arrived at the point where their eccentric radiicoincide, for at all times it is necessary, it free movement is to takeplace, that the one eccentric should move equally and oppositely to theother.

I claim:

1. In a remote control system having a transmitting medium in whichvariations occur from expansions and contractions thereof, mechanicallinkag for compensating said variations comprising a rectilineal guide,eccentrics oppositely revoluble about a common axis during compensatingmovements, and strap devices formed as sliders encircling saideccentrics and slidable in said guide, said eccentrics being normallyfree to adjust themselves by simultaneous turning movement under theinfluence of said variation but constituting together with the saidstrap devices and rectilineal guide a locked mechanism when thetransmission is operatively stressed.

2. In a. remote control system having a transmission means, two springloaded sliding members in operative connection with said transmissionmeans and gearing between the said members, said gearing comprising arectilineal guide, eccentrics oppositely revoluble about a common axisduring compensating movements by said members, and strap devices formedas sliders encircling said eccentrics and slidable in said guide,whereby said gearing permits simultaneous movement of the spring loadedsliding members in one and the same direction under the influence ofvariations due to expansion and contraction of the transmission meansand acts as an interlock between the said members when the transmissionis operatively stressed.

3. In a remote control system of the closed circuit type comprisingoutward and return transmission leads from and to the master control,the combination of spring loaded sliding member in connection withrespective leads, rack and pinion gears in driving connection withrespective members, eccentrics in driving connection with respectivegears and simultaneously but oppositely revoluble about a common axisduring compensating movements by said members, a rectilineal guide, and.strap devices formed as sliders encircling said eccentrics and slidablein said guide.

4. In a, remote control system of the closed circuit type comprising amaster control including a handle, and outward and return transmissionleads from and to the master control, the combination of spring loadedsliding members in connection with respective leads, rack and piniongearing in driving connection between said master control handle andsaid members, eccentrics in driving connection with respective gears andsimultaneously but oppositely revoluble about a common axis duringcompensating movements by said members, a rectilineal guide rockable bysaid handle, and strap devices formed as sliders encircling saideccentrics and slidable in said guide.

5. In a remote control system of the closed circuit type comprisingoutward and return transmission leads from and to the master control,the combination of spring loaded sliding members in connection withrespective leads, rack and pinion gear in driving connection withrespective members, eccentrics in driving connection with respectivegears and simultaneously but oppositely revoluble about a common axisduring compensating movements by said members, a rectilineal guide,strap devices formed as sliders encircling said eccentrics and slidablein said guide, and anti-friction rolling bodies interposed between saidsliders and said eccentrics.

6. In a remote control system of the closed circuit type comprisingoutward and return transmission leads from and to the master control,the combination of spring loaded sliding members in connection withrespective leads, rack and pinion gears in driving connection withrespective members, eccentrics in driving connection with respectivegears and simultaneously but oppositely revoluble about a common axisduring compensating movements by said members, a rectilineal guide,strap devices formed as sliders encircling said eccentrics and slidablein said guide, and antifriction rolling bodies interposed between saidsliders and said eccentrics in such manner that said rolling bodies areunder initial stress when the parts are assembled.

7. In a remote control system having a transmission means, two springloaded sliding members in operative connection with said transmissionmeans and gearing between the said members, said gearing comprising arectilineal guide, eccentrics oppositely and simultaneously revolubleabout a common axis during compensating movements by said members, strapdevices formed as sliders encircling said eccentrics and slidable insaid guide, a carrier revoluble about said axis, and locking meansmovably supported in said carrier and interengaging with said strapdevices in such manner as to permit said strap devices to performsimultaneous sliding movements in opposite directions but to preventthem from performing simultaneous sliding movements in one and the samedirection.

8. In a remote control system having a transmission means, two springloaded sliding members in operative connection with said transmissionmeans and gearing between the said members, said gearing comprising arectilineal guide, eccentrics oppositely and simultaneously revolubleabout a common axis during compensating movements by said members, strapdevices formed as sliders encircling said eccentrics and slidable insaid guide, a carrier plate disposed between said eccentric andrevoluble about said axis, and pin devices slidable laterally throughsaid carrier plate and having camming engagement; with the ends of saidstrap devices whereby the latter are permitted to perform simultaneousliding movements in opposite directions but are prevented fromperforming simultaneous sliding movements in one and the same direction.

9. In a remote control system of the closed circuit type comprisingoutward and return transmission leads from and to the master control,the combination of spring loaded sliding members in connection withrespective leads, rack and pinion gears in driving connection withrespective members, eccentrics in driving connection with respectivegears and simultaneously but oppositely revoluble about a common axisduring compensating movements by said members, a rectilineal guide,strap devices formed as sliders encircling said eccentrics and slidablein said guide, and an adjustable bearing pad interposed between one ofsaid sliders and said guide and operative for tightening said sliders insaid guide.

10. A compensator for a remote control system of the closed circuit typecomprising two spring loaded sliding members in connection withrespective circuit leads, rack and pinion gearings in driving connectionwith respective members, two eccentrics each in driving connection witha respective gearing and simultaneously but oppositely revoluble about acommon axis during compensatin movements by said members, strap devicesformed as sliders encircling said eccentrics, a fixedly mountedrectilineal guide for said strap devices to slide in, and locking meansoperating reciprocally between said strap devices for permittingsimultaneous sliding movements thereof in opposite directions butpreventing such movements in one and the same direction.

FRANCIS VIGIOR BROWN.

